This invention relates to a device for aligning a part and a substrate designed to receive it. It relates, in particular, to such a device adapted for mounting semiconductor microplates on a base carrying an electric circuit pattern.
Making an electrical and mechanical connection between a microplate and a substrate usually necessitates, before establishment of the connection, alignment of the plate with the substrate and then a second alignment of the plate-substrate assembly with a tool, e.g., a welding tool. There are devices in which the microplate is first oriented in relation to the tool and then integrated with that tool. The substrate is then aligned with the tool-microplate assembly.
That is why microplate mounting installations generally incorporate an alignment device containing, primarily, an XY moving table making it possible to move the part or the substrate in two orthogonal horizontal directions, the table being capable of turning on a vertical axis. The device also includes an optical device for monitoring the alignment operation. Schematically, each alignment operation, e.g., of a part and a substrate carried by the XY table, consists of moving the XY table in two orthogonal directions, so that the axes of the part and of the substrate are aligned, and then rotating the substrate, to angularly align it with the part. In most alignment devices, one finds that when the axis of the substrate does not coincide with the axis of rotation of the XY table, any rotation of the latter alters the position of the axis of the substate. It is then necessary, after rotation, to make a new XY adjustment in order to obtain perfect alignment.
In other present devices, the XY table is no longer made to turn on a fixed axis in relation to the mounting base of the installation, but it carries a support for the substrate, which is rotatably mounted on the XY table. It would then be sufficient to deposit the substrate on the support, so that its axis exactly matches the axis of rotation of the support, for the aforementioned problem to disappear. This entails, however, an additional alignment operation, which must, furthermore, be repeated in cases where the same substrate contains several sites for receiving parts. Another disadvantage of this approach is that the axis of rotation, no longer being fixed in relation to the mounting base of the installation, can deviate from the optical axis of the viewing device, which leads to new difficulties in then aligning the part-substrate assembly with the welding tool that is often also placed on the optical axis or at least on a parallel fixed axis. A shift between the optical axis and the part-support axis can further cause image distortions.
Still another disadvantage of the present devices is that, in order to make appreciable translations, e.g., to pass from one substrate site to another, it is necessary to use a slow moving XY table.
An object of this invention is to provide an alignment device which simplifies and accelerates alignment operations by eliminating the defects of the devices of the prior art.